Not applicable.
Not applicable.
1. Field of the Invention
The present invention relates to an apparatus for holding and guiding movement of a workpiece relative to a cutting or abrading member. The invention more particularly relates to an apparatus for holding and guiding movement of a wooden, metal, or other type of workpiece relative to a cutting or abrading member to assist an operator in cutting or abrading a circular perimeter. The invention finds application in any field wherein it is desirable either to provide a workpiece with a circular perimeter or to sand or otherwise abrade the circular perimeter of a workpiece. Examples of application of the present invention include use in woodworking or metal working.
2. Description of the Invention Background
Stationary woodworking saws such as, for example, band saws, scroll saws, and jig saws, may be used to provide a curved perimeter on a workpiece. In such applications, the wooden workpiece may be rotated or otherwise manipulated against the saw""s driven saw blade to create the desired perimeter shape. Providing a workpiece with a circular perimeter in this way may be especially difficult because it is difficult to manually manipulate the workpiece in a path relative to the saw blade that is perfectly or even substantially circular. Minor variations in the perimeter of the finished product from a symmetric circular shape may be evident to the naked eye. Also, manually manipulating the workpiece against the saw blade to form a circular perimeter can be time consuming because the precision required to rotate the workpiece dictates moving the workpiece very slowly relative to the saw blade. If a large circular perimeter is desired, the task may be impossible to complete on a typical band saw because of the relatively small surface area provided on standard workpiece support tables associated with such machines.
Even if a workpiece having a circular perimeter has been cut successfully, one may desire to sand the perimeter. Sanding the circular perimeter manually with, for example, a hand-held sander, may be difficult and time-consuming, and uneven application of the sander to the perimeter may destroy the circular character of the workpiece.
Devices are known for assisting an operator to cut a circular perimeter using a band saw. For example, the DELTA(trademark) Model No. 28-193 Circle Cutting Attachment (xe2x80x9cthe DELTA attachmentxe2x80x9d) includes a table attachment that is secured to the band saw table. The table attachment includes a series of holes spaced along its length, and into which a pin may be inserted. The pin extends a short distance above the top surface of the attachment. To cut a circle, the pin is secured to the workpiece at the desired central point of the circle, and the pin is inserted into an appropriate hole in the table attachment. The workpiece is then simply rotated against the saw blade about the central axis defined by the pin. The distance from the center of the selected hole to the saw blade will be the circular radius.
Although the DELTA attachment effectively produces circular perimeters, because the holes in the table attachment are at predetermined locations, the available circle sizes may be limited. Achieving certain circular diameters within the capability of the device may require fine adjustment of the position of the table attachment relative to the saw blade. Also, the table attachment can support only a limited workpiece size and, therefore, the maximum circular diameter that can be cut using the device is relatively limited. In addition, to cut a desired circular perimeter, at least one point on the desired circular perimeter must be exposed so that the saw blade may initiate the cut at that point and cut along the desired circular perimeter in one rotation of the workpiece. Thus, it may be necessary to pre-cut the workpiece so as to expose the starting point. Such pre-cutting increases complexity, requires additional time, and, if not executed carefully and precisely, may mar the workpiece and necessitate that it be discarded.
A circle cutting attachment is disclosed in U.S. Pat. No. 5,617,909, issued to Duginske. The attachment includes an auxiliary plywood table that is added to support larger workpieces on a band saw table. A track is provided in the auxiliary table. Within the track is place a stop with a drilled hole into which is pressed a sharpened nail. The stop is fitted into a slot of the track and secured therein by a set screw. To cut a circular perimeter, the distance between the nail and the saw blade represents the radius of the circle that will be cut. The Duginske design allows for placement of the center point of the desired circular shape at any fixed position along the track. However, as with the above-described known Delta attachment, in order to cut a desired final circular perimeter, a point on the desired perimeter must be accessible to the saw blade as the starting point for the cut.
Thus, considering the limitations of the above-described known work holding attachments, there exists a need for a workpiece holding apparatus that may be used to easily and quickly cut or abrade a circular perimeter on workpieces of various size, and without a need for careful and precise pre-cutting of the workpiece.
In order to address the forgoing needs, the present invention provides a workpiece holding apparatus for positioning a workpiece relative to a machine having a driven member such as a cutting or abrading member. The work holding apparatus includes a base having a workpiece support surface and a first track therein, and further includes a track-mounted member having a void therein. The void may be in the form of, for example, an open-ended slot defined, at least in part, by opposed first and second arms. The track-mounted member is selectively securable within the first track at a desired position along the first track. The work holding apparatus of the invention also includes a workpiece mounting member that is slidable within the void. The workpiece is attached to or otherwise mounted on the workpiece mounting member, the workpiece mounting member is disposed within the void, and the workpiece may be rotated on the track-mounted member about a point defined by the workpiece mounting member to contact the driven cutting or abrading member.
The present invention also is directed to a unique cutting method for cutting a workpiece on a device having a driven cutting member so as to provide a circular perimeter to the workpiece. The method includes providing an apparatus for positioning the workpiece relative to the cutting member. The apparatus generally includes: a base having a workpiece support surface and a track therein; a track-mounted member that is selectively securable along the track and that includes a void; and a workpiece mounting member that is movable within the void. The workpiece is mounted on the workpiece mounting member, and the workpiece mounting member is disposed within the void. The workpiece is rotated to contact the cutting member, while simultaneously advancing the workpiece mounting member along the void toward the cutting member.
The workpiece holding apparatus of the present invention may be adapted to be secured to the workpiece support table of a cutting or abrading device and may be used to provide workpieces with circular perimeters in a quick and efficient manner. The workpiece holding apparatus of the invention may be adapted for use with workpieces of relatively large dimensions and may be used to cut circular perimeters by way of the foregoing unique cutting method. By way of the unique cutting method, the operator need not pre-cut the workpiece and expose a point on the desired circular perimeter as the starting position for the cut created by the driven cutting member. The apparatus of the invention also may be adapted to assist in the quick and efficient abrading of existing circular perimeters of workpieces.
Thus, the present invention addresses deficiencies in the existing workpiece holding devices used for cutting and/or abrading circular perimeters. Those of ordinary skill will readily appreciate the foregoing and other details, features, and advantages as the following detailed description of embodiments of the invention proceeds.